The production of semiconductor devices often involves forming microelectronic devices on a microelectronic substrate, such as a silicon wafer. These microelectronic devices may include for example transistors, resistors, capacitors, combinations thereof, and the like, which may be connected to one another and other components via a metallization pattern (metal interconnects), so as to form one or more integrated circuits.
Various processes are known for forming integrated circuits on a microelectronic substrate. Among those processes is the so-called “damascene process,” which typically involves using a photoresist and etching processes to selectively remove material from the microelectronic substrate or other dielectric material. For example, the photoresist material may be patterned on a dielectric material, after which the dielectric material may be etched to form a holes or “trench” (hereinafter, opening) consistent with the photoresist pattern. After etching the photoresist may be removed (e.g., using an oxygen plasma or selective wet etching) and the opening is then filled with a conductive material such as a metal or metal alloy, e.g., via physical vapor deposition, chemical vapor deposition, electroplating, or some other mechanism as will be understood to those skilled in the art.
Over time the size of microelectronic devices has shrunk dramatically, while their complexity has increased. As a result, it is becoming increasingly difficult to form suitable openings (e.g., vias, traces, etc.) using conventional masking materials and etch chemistry. Metals and metal nitrides such titanium and titanium nitride are being increasingly used by integrated circuit manufacturers as hard masking materials, as well as a barrier layer or conductive layer that may be useful in a microelectronic device or the production thereof. For example, a bilayer of titanium and titanium nitride may be used as a fill barrier during the production of gates and/or gate contacts in microelectronic transistors, such as non-planar transistors.
With the foregoing in mind, layers of Ti and TiN are often deposited in such a manner that they are present on the surfaces they are intended to cover, but also adjacent surfaces as well. Because titanium is conductive, the presence of it on such adjacent surfaces may cause problems, particularly if the layers create an electric pathway between multiple microelectronic devices or components thereof. Indeed, the titanium may cause an electrical short in such instances, which may prevent its associated microelectronic device from functioning properly.
To address this issue, technologies such as polishing, high density plasma etching and hydrofluoric (HF) acid based wet etching chemistries have been developed in an attempt to selectively remove titanium and titanium nitride from workpieces such as microelectronic devices. While such technologies are effective, their use often results in damage to the surface of the workpiece, and/or structures that are in proximity to the target titanium and titanium nitride. For example, titanium and titanium nitride are often used in proximity to metals, oxides, insulating materials, dielectric materials, etc., any or all of which may attacked by a high density plasma or conventional HF acid based wet etching chemistry. Therefore high density plasma or conventional HF acid wet etching chemistries may not be ideal in circumstances where it is desired to etch titanium and/or titanium nitride in the presence of metals, oxides, and/or dielectric materials.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art.